3.5 mm TRRS — Headset Standard (Audio + Mic)
CTIA wiring: tip L, ring 1 R, ring 2 GND, sleeve MIC. OMTP wiring swaps GND and MIC.
Pinout
Pinout data not yet populated for this connector.
Specifications
| Diameter | 3.5mm |
|---|---|
| Pole count | 4-pole TRRS |
| Signal topology | single-ended-stereo + microphone |
| Intended use | Smartphone and gaming headset with inline microphone |
About this connector
The 3.5 mm TRRS (tip-ring-ring-sleeve) adds a fourth contact to the standard TRS, carrying an inline microphone signal. Two competing pole-assignment standards exist: CTIA (Apple/Google/the rest of the industry) places ground on ring 2 and mic on sleeve; OMTP (older Nokia, some legacy Android) inverts them.
Plug an OMTP headset into a CTIA host and you get audio in your microphone and mic-level noise in your headphones. Modern smartphones almost universally auto-detect, but pre-2014 hardware will simply fail.
Distinct from balanced 2.5 mm TRRS — same connector geometry, completely different signal allocation. See the 2.5 mm TRRS entry for the balanced-stereo variant. Related: the 3.5 → RCA adapter ignores the mic pole entirely.